Fuel oil additive



aim-m United States Patent FUEL OILADDITIVE Arthur Churchill, Oakmont, and Edward Mitchell, Valencia, Pa., assignors to Gulf Research 8: Development Company, Pittsburgh, Pa., a corporation of Delaware N0 Drawing. Filed Dec. 2, 1957, Ser. No. 699,910 Claims. (Cl. 4464) This invention relates to improving the combustion characteristics of hydrocarbon oil 'fuels that normally tend to form substantial amounts of soot and smoke during combustion, and to improve agents adapted for usein such fuels.

The petroleum industry has encountered a serious problemin satisfying the demand for middle distillate an'd'heavier fuel oils that can be burnediin fuel burners such as those of the atomizing type and of the rotary wall'flame type with little or no accompanying formation of smoke or soot. Oils that are normally burned in oiljburners of vthe types indicate are those of Number 2 grade or heavier, although lighter'oils "can be used. Although some smoke and soot formation will normally accompany combustion of any suitable oil in burners arms type indicated, especially where less than optimum combustion conditions are used, the problemis serious in the case of oils having an .API gravity of less than 34", as substantialsmoking and soot formation will occur during combustion of such oils even when favorable combustion conditions are employed. The poorcombustion characteristics of such oils are considered attributable to the relatively high proportion of aromatic components containedtherein. Fuel oils havingan API gravity of less than 34 will normally contain in excess of about 20percen t aromatics, for example, 25, 40, or even 60 'percentor more of aromaticcomponents, whereas lighter fuel oilsvn'll normally contain a substantially lower proportion of aromatics, for example, percent .or less. In the case of distillate oils, a high aromatics content usually signifies a large proportion of cracked distillates, as the latter are relatively rich in aromatics. The proportion of catalytically cracked distillate fuel oils in commercially marketed fuel oils has increased in recent years not withstanding the relatively inferior burning qualitieszof such oils, because the demand for :fuel oils ofcomparable boiling range has exceeded the available supply ofstraight-run oils.

.Not only do low-gravity distillate oils containing large proportions of cracked distillates, that is,-oils rich in aromatics, form greater quantities of soot during combustion than straight-run, high-gravity distillate oils, or similar oils low in aromatics, but also such oils form soot of dilferent quality. Soot :formed from the latter oils is a loosely deposited, low-density material having a low coeificient of heat transfer, whereas soot from-the .former oils is resinous, much denser and has a higher coeflicient of heat transfer.

While the problem of clean'combustion is especially serious in the case of distillate fuels, where fuel-quality is of major importance, a combustion problem also aexists in. tbe case of residualfuel .oils. Similarly as the .middle distillate fuel oils, the residual fue s have an API .gravity less :than 34 (API gravity for typical .6 fuel oils varies in the range of 5 to 15), and t-hey also-fre 7 2,971,827 Patented Feb. 14, 1961 1 2 quentlycontain'exceptionally large proportions, for example 60 percent or more, of aromatic components. Residual fuels can contain relatively low-boiling aromatic components as well as higher boiling materialgas they are frequently diluted or cut-back with lower boiling cracked distillate oils in order to reduce the viscosity of the heavier oils.

Although the combustion of fuel oils having an API gravity of less than 34, and consequently a relatively tiontof fuelfoils. is'iobjectionablenot only from the stand.-

point 'of cleanliness and air pollution, but also in that smoke and soot "lead to stack deposits which may reduce burner draft and/or causethestack temperature to rise to adange'rous point.

The present invention relates to improved fuel oil compositions comprising'hydrocarbon fuel oils that have an API gravity of less than 34?, which compositions have reduced smoke and soot forming tendenciesduring combustion, whereby such fuel oil compositions .are rendered 'more suitable for use as fuels in domestic oil burners of various kinds, such as heating furnaces of the atomizing or rotary wall flame type, combustion gas"turbine-enginesjdiesel enginesand the like. We have found that such improved fuel compositions can b'e'iob, tained by incorporating in a fuel oil of'the'type described and that normally tends to form substantial 'smoke and soot during combustion, a small amount of a salt ofan 'oilsoluble hydrocarbon sulfonic acid and hydrazine, For example, excellent results have been obtained with monohydrazinium polydodecylbenzene sulfonate. SpeF cific examples of other suitable salts include dihydrazinium polydodecylbenzene sulfonate and mono and dir salts of hydrazine and oil-soluble petroleum sulfonic acids. The invention includes fuel oils containing these salts 'aswell as the salts themselves.

The-exact mechanism by which the hydrazinium sulfonates disclosed herein function to reduce smoking 'sooting during combustion of fuel oils of the class dis, closed has not been definitely determined, and accord: ingly, we do'not intend thepresent invention to be limited to any particular theory of operation. It may thatthe hydrazinium sulfonates reduce the ignition temperature of the oil, thus enabling more complete com.- bustion and at the same time reducing the possibility of thermal-cracking of the oil prior to combustion. 0n the other hand, itvmay be that the hydrazinium su fq nates cause the oil to burn at a higher temperature, "thus facilitating more complete combustion. Regardless of the mechanism by which the agents disclosed herein func tion, available experimental evidence shows that'adefinite reduction .in'smoke and soot forming tendencies obtained by the use of small amounts of these agents in fuel oils that normally tend to promote excessive soot and smoke formation during combustion in 'atomizing type burners.

The i ydrazinium lf QIcS of th s in en on prepared in {any conveni n manne For examp e they can be p ep r dv y i ec e ct o of h d az n -w zdesired cil-selub e t ltonic acid a in a in proportion in the range of about 1:1 to 1:2. The neutralization re action takes place spontaneously at atmospheric conditions of temperature and pressure. However, other conditions can be used For example, mild heating, say up to 160 F., can be resorted to provided the heat is insufiicient to decompose the addition salt.

The nature of the acidic portion of the hydrazine salts is important insofar as the combustion-improving characteristics of the salts are concerned. Thus, salts of hydrazine and oil-soluble hydrocarbon sulfonic acids have been found to possess exceptional advantages from a combustion-improvement standpoint. For example, especially effective results have been obtained with salts of hydrazine and long-chain aliphatic hydrocarbon-substituted benzene sulfonic acids, particularly the monohydraz'inium sulfonate, that is, the salt produced by reacting hydrazine and a long-chain aliphatic hydrocarbon substituted benzene sulfonic acid in approximately equimolar proportions. By long-chain aliphatic hydrocarbon-substituted benzene sulfonic acid is meant a henzene'sulfonic acid having as a nuclear substituent a hydrocarbon chain of a length and configuration such as to impart fuel oil solubility to the acid. The long-chain aliphatic hydrocarbon groups can be saturatedor unsaturated, straight or branched chain and/orsubstituted with substituents that contain elements or groups other than carbon and hydrogen and that do not interferewith oil-solubility or other fundamental characteristics of the ultimate salt, for example, oxygen, hydroxyl, carbonyl, amino, halogen, sulfur, mercapto and'the like. Examples of oil-soluble, aliphatic hydrocarbon-substituted benzene sulfonic acids that possess sufiicient fuel oilsolue bility to form suitable salts for the purposes of this invention include ortho and para tetradecyl, hexadecyl, octadecyl, triacontanyl and polydodecyl benzene sulfonic acids. The invention is not limited to long-chain aliphatie hydrocarbon-substituted benzene sulfonic acid.

salts, however, and salts of other oil-soluble hydrocarbon sulfonic'acids can be used. Thus, oil-soluble petroleum sulfonic acids, that is, mahogany acids, can also be used to form monoand dihydrazinium salts useful for the purposes of the present invention.

The hydrazinium sulfonates included by this invention are added to the fuel oils in a proportion sufiicient substantially to reduce the smoking tendencies of the oil. Since the various materials disclosed herein are not necessarily exact equivalents, the'optimum proportion will vary according to the nature of the particular agent added, and to some extent according to the nature of thefuel oil. The type of fuel oil burner employed can also affect the optimum proportion of agent to be added. Within thelimits of these considerations, we have found that-best results are obtained by addition to the fuel oils of small amounts of the hydrazinium sulfonates disclosed herein. Thus, noticeable improvement usually will be obtained by addition of as little as 0.02 weight percent of these materials to the fuel oils, and a major improvement will be obtained by the addition of about 0.05 weight percent to the fuel oil. Normally, it will not be necessary to add the hydrazinium sulfonates in excess of 0.2 weight percent of the composition, although in some cases it may be desirable to employ as much as 0.5 percent of the salt.

a The compounds disclosed herein may be incorporated in the fuel oil in any suitable manner. Thus, the hydrazinium sulfonates can be added to the fuel oil either as such or in the form of concentrated mineral oil solutions. After addition of these materials to the oil, some circulation of the oil is desirable to facilitate early formation of a homogeneous composition, but this is not absolutely essential.

In order to demonstrate the effectiveness of the come bustion improvement agents disclosed'herein, hydrazine sulfonate was incorporated in a No. 2 fuel 'oil that nor mally tends toform smoke and soot on combustion, and

the thus-compounded fuel oil was-"tested for smoking tendencies by combustion in an atomizing type burner. The test was carried out in a domestic oil burner (Timken, Model OFH60Hi-Furnace). Conventional burner controls were associated with the test apparatus in con junction with electrical timerrelays to provide a 20 minute on 10 minute off cycle of burner operation. After permitting a warm-up of at least. one 20 minute on cycle of burner operation with maximum combustion air, smoke spot and CO reading were taken at the middle of each on cycle for 7 cycles using different air gate settings to regulate the quantity of combustion air. Changes of gate setting were made during burner off phases of the cycle. Smoke spot readings were obtained by withdrawing flue gas from a sampling probe installed .the chimney pipe through a disc of No. 4Whatman filter paper one inch in diameter for 2 minutes. A vacuum pump was used to maintain a pressure differential of 2% inches Hg across the disc. The smoke spot reading was then determined by means of a photocell meter which had been calibrated using a Shell smoke spot chart graduated in increasing shades of black ranging from zero (clean disc) to 9 (black disc) as the standard. The CO, readings were obtained by withdrawing'fiue gas through a sampling probe installed in the chimney pipe (according to United States Department of Commerce Bulletin CS104-46) and by analyzing the flue gas for percent CO in an Orsat-type flue gas analyzer.

The test fuel, hereafter referred to as test fuel A,'was an uninhibited commercial-type, 30 API gravity No. 2 fuel oil having an aromatics content of about 45 percent and consisting of 36.4 volume percent straight-run No. 2 fuel oil distillate and 63.6 volume percent catalytically cracked No. 2 fueloil distillate. Percentages given herein are by weight of the composition unless otherwise specified. The term No. 2 fuel oil is defined in ASTM Standards on Petroleum Products and Lubricants for November 1956 as a distillate oil for general purpose domestic heating for use in bumers not requiring No. 1 fuel oil (an oil intended for use in vaporizing pot-type burners) and having the following inspections:

Viscosity, SUS, 100 F. (max.) Viscosity, kinematic, cs., 100 (max) 4.3 Gravity, API (min.) 26

The combustion improvement agent subjected to the foregoing test was the monohydrazinium salt of oil-soluble alkylbenzene sulfonic acids. The monohydrazinium sulfonate employed in the test was prepared by reacting hydrazine hydrazine, 5% water) at room temperature in approximately equimolar proportions with a 47 percent solution in oil of oil-soluble alkylbenzene sulfonic acids having a combining weight (average molecular weight) of about 445, with the number of alkyl carbon atoms per molecule averaging about 20.5. The reaction mixture was cooled during addition of hydrazine to remove heat of reaction and to maintain the reaction mixture at about room temperature. The reaction product was diluted with hexane and filtered to remove insoluble matter, principally hydrazine sulfate. Hexane was then removed by evaporation on a steam bath. The resulting sulfonate comprised an approximately 50 percent solution in oil of monohydrazinium oil-soluble alkylbenzene sulfonate. j 7 In order to demonstrate the extent of the improvement obtained withthe test additive, test fuel Awas also subjected to the test without'addition of the combustion improvement agent. l g

, In'the following table there are tabuia'tedthe'results or tained inthe combustion tests describedabove. below:

Table A Smoke Disc Number at- Gomposltion Avg.

3% 8.5% 0% 9.5% 11% 12% Smoke 00, 00 00, '00, c0, 0o, 00, Spot No.

1. Test FuelA 0.20 5.65 5.05 4.45 3. 75 2.70 2. 70 4.36 2. Test Fuel A plus 0.05 Wt. percent (active component) HydrazineSulfonate. 4.95 4.10 3.50 3.05 2.65 2.15 2.00 3.20

The data presented in the foregoing table indicate that Table C a marked improvement in burning qualities of fuel oils is obtained by incorporation therein of the combustion Gravity, Percent Smoke improvement agents of this invention. Thus, 0.05 percent Fuel Oil e Disc hydrazine sulfonate in test fuel A produced an average 108 Improvement of more than 26 percent in the smoke spot L FCC 2 Distillate 258 42 4. 4 number. 2. 50/50 by Vol. Eastern Venezuela St.

The addition agent and the test fuel described in the 3 Run and FCC 53-8 3'3 foregoing tests are illustrative only. Substitution of other 4: :9 2410 2:2 sulfonates disclosed herein in the same or equivalent pro- No 2 Dist 32 1 23 2 1 3 portions in the foregoing test compositions will produce 30 6. TOO Rafiina t III 34:5 16:3 016 similar benefits. Examples of other fuel compositions in- 1 35.6 15 6 0 6 eluded by this invention are shown in thefollowing table. Blend of Kerosene and Gas-Oil, 7

50 by VOL--- 41. s 13.9 0.4 9. Kerosene 42.6 14.0 0.7 Table B From the results shown in the foregoing table, it will Base on Addmon Agent 3275322 be seen that fuel oils having an API gravity of less than Percent Add-A about 34 and an aromatics content of about 20 percent or more produce a relatively high smoke spot number NmzFuel Oil g gf fi which is a measure of the smoking and sooting tenden- Z i nfj cies of the oils. Even a small decrease in API gravity of D0 giggg fi- M such lower gravity oils normally results in a disproporhogany tionate increase in the smoke spot rating. In contrast, NOAFueIOiHNOG 1 40+ lfff M oils having a gravity above 34" API produced a low Fuel Oil red.to smoke spot number, and httle difference in smoke spot ia 'g g figggnumber resulted among such oils despite substantial dif- Gas 011. ferences in API gravity.

The oil-soluble petroleum sulfonic acids whose salts Avg. M.W1ormeh0 an acid=435. are employed in the fuel oil compositions of this invention are the sulfonic acids known as mahogany acids.

It is emphasized that the problem with which the present invention is concerned involves only fuel oils that are normally burned in fuel oil burners that utilize middle distillate and heavier oils and that normally exhibit severe smoking and soot forming tendencies in such usage. As indicated, such oils are those having an API gravity less than 34. The problem with which this invention is concerned is especially serious in the case of distillate fuel oils of the type described because combustion quality is of primary consideration with such oils. Although a clean combustion problem also exists in the case of residual fuel oils suitable for use in atomizing type burners, the relatively low price of such fuels and the absence of a superior competitive fuel renders the problem less serious in the case of such oils.

In order to demonstrate the nature of the problem with which the present invention is concerned, a number of fuel oils having varying densities and aromatics contents were subjected to a combustion test substantially similar to that described above, but carried out in a Timken Vertical Rotary Wall Flame Burner, Model F, installed in a Weil-McLain Type 4-S-l9 steam boiler, in order to determine the burning characteristics of the oils. These tests were carried out at 11.0% CO in the flue gas, a recommended figure for the burner model in ,ques- These acids, together with water-soluble green acids, are produced during the acid refining of lubricating oil distillates. Methods of recovering these acids are well known and form no part of the invention.

If desired, the fuel oil compositions of this invention may contain in addition to the compounds previously discussed oxidation inhibitors, corrosion inhibitors, antifoam agents, ignition quality improvement agents, sludge inhibitors, color stabilizers and other addition agents adapted to improve the oils in one or more respects.

Obviously, many modifications and variations of the invention as herein described may be resorted to without departing from the spirit or scope thereof. Therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A fuel oil composition comprising a major amount of a hydrocarbon fuel oil that hasan API gravity less than about 34, and that normally tends to form smoke and soot during combustion, and containing a small amount, suflicient to reduce the smoke and soot forming tendencies of the oil, of a salt of hydrazine and an oilsoluble hydrocarbon sulfonic acid se ected from the group consisting of petroleum sulfonic acids and long-chain aliphatic hydrocarbon-substituted benzene sulfonio acids.

. 6 tion. The results of the tests-are presented "in Table (2 2 The composition of claim 1 where said fuel oil is a distillate fuel oil. a

3. The composition of claim 1 where said small amount is about 0.02 to about 0.5 percent by weight of the composition.

4. The composition of claim 1 where said member is a salt of hydrazine and an oil-soluble, long-chain aliphatic V hydrocarbon-substituted benzene sulfonic acid.

3. The composition of claim 1 Where said member is a monohydrazinium salt of an oil-soluble alkylbenzene sulfonic acid containing 14 to 36 alkyl carbon atoms.

6. The composition of claim 1 where said member is a salt of hydrazine and oil-soluble petroleum sulfonic acids. 7. A salt of hydrazine and an oil-soluble, long-chain aliphatic hydrocarbon-substituted benzene sulfonic acid.

8. A salt of hydrazine and oil-soluble petroleum sulfonic acids.

9. A monohydrazinium salt of an oil-soluble alkylbenzene sulfonic acid containing 14 to 36 alkyl carbon atoms.

10. A fuel oil-soluble salt of hydrazine and an oilsoluble hydrocarbon sulfonic acid selected from the group consisting of petroleum sulfonic acids and long-chain aliphatic hydrocarbon-substituted benzene sulfonic acids, said salt being capable of reducing the smoke and soot forming tendencies of hydrocarbon fuel oils.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES The Chemistry of Hydrazine, by Audrieth, John Wiley and Sons Inc., 1951, pp. 224-232.

UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No. 2,971,827 February 14, 1961 Arthur V, Churchill et al It is hereby certified'that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 18, for "improve" reed improvement column 5, Table B, column 4, second line thereoi, Tor

"p-C read p-C column 7, line 9, for "3., The

24' composition" read 5; The composition Signed and sealed this 20th day of June F961:

(SEAL) Attest:

' Attesting Officer Commissioner of Patents 

1. A FUEL OIL COMPOSITION COMPRISING A MAJOR AMOUNT OF A HYDROCARBON FUEL OIL THAT HAS AN API GRAVITY LESS THAN ABOUT 34*, AND THAT NORMALLY TENDS TO FORM SMOKE AND SOOT DURING COMBUSTION, AND CONTAINING A SMALL AMOUNT, SUFFICIENT TO REDUCE THE SMOKE AND SOOT FORMING TENDENCIES OF THE OIL, OF A SALT OF HYDRAZINE AND AN OILSOLUBLE HYDROCARBON SULFONIC ACID SELECTED FROM THE GROUP CONSISTING OF PETROLEUM SULFONIC ACIDS AND LONG-CHAIN ALIPHATIC HYDROCARBON-SUBSTITUTED BENZENE SULFONIC ACIDS.
 10. A FUEL OIL-SOLUBLE SALT OF HYDRAZINE AND AN OILSOLUBLE HYDROCARBON SULFONIC ACID SELECTED FROM THE GROUP CONSISTING OF PETROLEUM SULFONIC ACIDS AND LONG-CHAIN ALIPHATIC HYDROCARBON-SUBSTITUTED BENZENE SULFONIC ACIDS, SAID SALT BEING CAPABLE OF REDUCING THE SMOKE AND SOOT FORMING TENDENCIES OF HYDROCARBON FUEL OILS. 